Earth moving wagons are known for use in excavation and mining operations. These wagons have traditionally been connected to a dedicated tractor by a gooseneck extension hitch affixed to the wagon and pivotally mounted on the dedicated tractor. Other uses of the tractor were not possible.
The advantage of the use of a gooseneck extension hitch is that a 90 degree steering angle is allowed for increased maneuverability. This maneuverability is desired when used underground, where space is limited. The gooseneck extension hitch provides a required clearance above the two rear wheels of the tractor to accommodate tight angle turns of the tractor.
Traditionally, the wagon associated with a gooseneck extension connection includes only two wheels for carrying the load. Some of these wagons are tipped up to release a load while other wagons have an ejection system to force a load rearwardly from the wagon.
As a wagon is raised or tipped to dump a load, the instability of the wagon greatly increases. This is due to having the load in an elevated position. Combining the elevated load with uneven working surfaces can result in overturning of the vehicle. If the tractor is turned 90.degree., this situation is further aggravated.
In the ejection system, a piston cylinder arrangement is subject to damage during loading of the wagon. In addition, the available space for cylinder mounting and required ejector travel requirements necessitate greater than two stage hydraulic telescopic cylinders. The force required to retract the ejector with these cylinders necessitates the use of multiple or oversized cylinders.